XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3319
of other silicate gangue was higher. This suggests FA1 was
prone to unselective recovery of silicate minerals compared
with FA2, likely due to the higher rosin content (2.4%).
The highest lithium recovery (97.0%) was observed
when FA2 was combined with 5% HYR, but this produced
the lowest concentrate grade of 4.03% Li2O. A similar lith-
ium recovery was produced with FA2 and NCY (96.6%),
however, the concentrate grade was considerably higher
at 4.33% Li2O – although still considerably lower than
pure FA2 (4.65% Li2O). Although the increase in lithium
recovery was similar when either TOR was added to FA2
(1.8–2.2%), the significant decrease in concentrate grade
with 5% HYR suggests the two TORs may have a different
impact on collector adsorption. This was supported by the
differences in iron and silicate gangue recovery between the
two collectors when added to FA2.
Figure 1b. and 1c. highlight that addition of NCY
to FA2 resulted a notable increase in iron recovery from
67.6% to 73.6% – the highest of all tests – with a rela-
tively high Fe2O3 assay and a low Li2O assay (Figure 1a.).
However, when HYR was added to FA2, the iron recovery
to the rougher concentrate increased to only 72.2%, and
it produced the lowest Fe2O3 and Li2O assays (Figure 1a.
and 1b.). The lower Li2O and Fe2O3 concentrate grade
with HYR and FA2 was a result of increased silicate gangue
recovery as indicated by the highest K2O and Na2O recov-
eries (18.2 and 11.8%, respectively). While the addition of
both TORs to FA2 increased recovery of all gangue miner-
als, the initial observation suggests that NCY was slightly
more selective against silicate gangue minerals but appeared
to promote flotation of iron-bearing gangue minerals with
spodumene. Meanwhile, with HYR +FA2, selectivity was
reduced, causing an increase in both iron and silicate gangue
recovery and increased dilution of the rougher concentrate.
A similar (yet less apparent) observation was made
when NCY and HYR were added to FA1. Both TORs
increased lithium recovery and reduced Li2O concentrate
grade. The increase in lithium recovery was similar with
both TORs added to FA1, but only by 0.8–1.1%, which
was less significant than the increase of 1.8–2.2% observed
with FA2. Similarly, there was less of an impact on the
rougher concentrate grade, as it was only reduced to about
4.40% from 4.52% Li2O with FA1. The plots in Figure 1b.
and 1c. show that the addition of NCY to FA1 had a simi-
lar effect as when added to FA2, resulting in a higher iron
recovery. Likewise, when HYR was added to FA1, there was
a higher recovery of both silicate and iron-bearing gangue
in the rougher concentrate.
A test was conducted to increase the pH during
rougher flotation to pH 9.25 for rougher flotation using
the blend of FA1 and 5% NCY. The higher flotation pH
increased iron recovery and Fe2O3 grade in the concen-
trate, while producing a lithium recovery like that of pure
FA1 (Figure 1). The result suggests that floating at pH 9.25
with NCY selectively increased the flotation of iron-bearing
minerals over spodumene. However, further investigation is
required to confirm if the effect of pH was pronounced in
the presence of NCY, or if it is a general trend with TOFAs.
The results shown in Figure 1c. and 1d. reveal that the
relationship between iron and lithium recovery and Li2O
and Fe2O3 concentrate grade have a positive correlation,
suggesting that selective rejection of iron minerals while
maintaining high lithium recoveries and Li2O grade will
be very difficult with TOFAs, regardless of rosin content.
The NCY test results in relation to other collector blends
(Figure 1c. and 1d.), indicated that the presence of NCY
preferentially increases iron recovery. Similarly, it appeared
that HYR reduced selectivity but did so with no clear pref-
erence between iron and silicate gangue minerals.
The strong linear relationship in Figure 2 between the
grade and recovery of K2O and Na2O confirms the recov-
ery of silicate gangue minerals increased with the addition
of both TORs, however, the increase is highest when HYR
is added to FA2. On both plots in Figure 2, the points rep-
resenting FA1 (solid dot) and FA2 (hollow dot) produced
the lowest gangue mineral recoveries, with FA2 being low-
est for both elements. Therefore, increasing the rosin con-
tent in TOFA collectors led to an unselective increase in
silicate gangue recovery to the rougher concentrate and a
slight increase in lithium recovery. This observation aligns
with those made by Filippov et al. (2018), where increasing
rosin content increased overall recovery but had a negative
impact on collector selectivity.
Rosin Composition on Flotation Performance
The rougher flotation results in Figures 1 and 2 confirmed
that increasing the rosin content in TOFA collectors by
adding TOR increased lithium recovery and decreased
overall selectivity. The different impacts of NCY and HYR
on selective gangue rejection – higher iron recovery with
NCY and higher overall gangue recovery with HYR – may
be attributed to differences in rosin composition of the four
collector blends.
As shown in Table 2, TOFA collectors FA1 and FA2
have different rosin contents of 2.4 and 0.8%, respectively.
Because of this, the 5% TOR additions always resulted in
a higher total rosin content in the FA1 blends compared
to FA2 blends. It was also observed that TOR additions to
FA2 had a greater impact on flotation performance com-
pared to FA1, suggesting that the overall rosin content is
of other silicate gangue was higher. This suggests FA1 was
prone to unselective recovery of silicate minerals compared
with FA2, likely due to the higher rosin content (2.4%).
The highest lithium recovery (97.0%) was observed
when FA2 was combined with 5% HYR, but this produced
the lowest concentrate grade of 4.03% Li2O. A similar lith-
ium recovery was produced with FA2 and NCY (96.6%),
however, the concentrate grade was considerably higher
at 4.33% Li2O – although still considerably lower than
pure FA2 (4.65% Li2O). Although the increase in lithium
recovery was similar when either TOR was added to FA2
(1.8–2.2%), the significant decrease in concentrate grade
with 5% HYR suggests the two TORs may have a different
impact on collector adsorption. This was supported by the
differences in iron and silicate gangue recovery between the
two collectors when added to FA2.
Figure 1b. and 1c. highlight that addition of NCY
to FA2 resulted a notable increase in iron recovery from
67.6% to 73.6% – the highest of all tests – with a rela-
tively high Fe2O3 assay and a low Li2O assay (Figure 1a.).
However, when HYR was added to FA2, the iron recovery
to the rougher concentrate increased to only 72.2%, and
it produced the lowest Fe2O3 and Li2O assays (Figure 1a.
and 1b.). The lower Li2O and Fe2O3 concentrate grade
with HYR and FA2 was a result of increased silicate gangue
recovery as indicated by the highest K2O and Na2O recov-
eries (18.2 and 11.8%, respectively). While the addition of
both TORs to FA2 increased recovery of all gangue miner-
als, the initial observation suggests that NCY was slightly
more selective against silicate gangue minerals but appeared
to promote flotation of iron-bearing gangue minerals with
spodumene. Meanwhile, with HYR +FA2, selectivity was
reduced, causing an increase in both iron and silicate gangue
recovery and increased dilution of the rougher concentrate.
A similar (yet less apparent) observation was made
when NCY and HYR were added to FA1. Both TORs
increased lithium recovery and reduced Li2O concentrate
grade. The increase in lithium recovery was similar with
both TORs added to FA1, but only by 0.8–1.1%, which
was less significant than the increase of 1.8–2.2% observed
with FA2. Similarly, there was less of an impact on the
rougher concentrate grade, as it was only reduced to about
4.40% from 4.52% Li2O with FA1. The plots in Figure 1b.
and 1c. show that the addition of NCY to FA1 had a simi-
lar effect as when added to FA2, resulting in a higher iron
recovery. Likewise, when HYR was added to FA1, there was
a higher recovery of both silicate and iron-bearing gangue
in the rougher concentrate.
A test was conducted to increase the pH during
rougher flotation to pH 9.25 for rougher flotation using
the blend of FA1 and 5% NCY. The higher flotation pH
increased iron recovery and Fe2O3 grade in the concen-
trate, while producing a lithium recovery like that of pure
FA1 (Figure 1). The result suggests that floating at pH 9.25
with NCY selectively increased the flotation of iron-bearing
minerals over spodumene. However, further investigation is
required to confirm if the effect of pH was pronounced in
the presence of NCY, or if it is a general trend with TOFAs.
The results shown in Figure 1c. and 1d. reveal that the
relationship between iron and lithium recovery and Li2O
and Fe2O3 concentrate grade have a positive correlation,
suggesting that selective rejection of iron minerals while
maintaining high lithium recoveries and Li2O grade will
be very difficult with TOFAs, regardless of rosin content.
The NCY test results in relation to other collector blends
(Figure 1c. and 1d.), indicated that the presence of NCY
preferentially increases iron recovery. Similarly, it appeared
that HYR reduced selectivity but did so with no clear pref-
erence between iron and silicate gangue minerals.
The strong linear relationship in Figure 2 between the
grade and recovery of K2O and Na2O confirms the recov-
ery of silicate gangue minerals increased with the addition
of both TORs, however, the increase is highest when HYR
is added to FA2. On both plots in Figure 2, the points rep-
resenting FA1 (solid dot) and FA2 (hollow dot) produced
the lowest gangue mineral recoveries, with FA2 being low-
est for both elements. Therefore, increasing the rosin con-
tent in TOFA collectors led to an unselective increase in
silicate gangue recovery to the rougher concentrate and a
slight increase in lithium recovery. This observation aligns
with those made by Filippov et al. (2018), where increasing
rosin content increased overall recovery but had a negative
impact on collector selectivity.
Rosin Composition on Flotation Performance
The rougher flotation results in Figures 1 and 2 confirmed
that increasing the rosin content in TOFA collectors by
adding TOR increased lithium recovery and decreased
overall selectivity. The different impacts of NCY and HYR
on selective gangue rejection – higher iron recovery with
NCY and higher overall gangue recovery with HYR – may
be attributed to differences in rosin composition of the four
collector blends.
As shown in Table 2, TOFA collectors FA1 and FA2
have different rosin contents of 2.4 and 0.8%, respectively.
Because of this, the 5% TOR additions always resulted in
a higher total rosin content in the FA1 blends compared
to FA2 blends. It was also observed that TOR additions to
FA2 had a greater impact on flotation performance com-
pared to FA1, suggesting that the overall rosin content is